In this image provided by KDKA- TV emergency personal respond to a shooting at the scene near Brashear High School, Nov. 13, 2013, in Pittsburgh.
Three students were shot and wounded Wednesday afternoon minutes after a Pittsburgh high school was dismissed for the day, police said.
Six "persons of interest" were taken into custody for questioning, acting Police Chief Regina McDonald said at a news briefing two hours after the 2:50 p.m. shooting.
The three students suffered non-life-threatening injuries when they were ambushed outside Brashear High School as they walked to their car, said Pittsburgh school district spokeswoman Ebony Pugh. Two are 17 and one is 16 years old.
Police spokeswoman Diane Richard said the shooting may have been retaliation for an Oct. 18 "incident" that put the school in lockdown for a week. She said the incident involved a fight and may have been drug-related.
Police reported that gunfire came from a hill overlooking the school. There were conflicting reports on whether there was one gunman or possible three shooters.
One student was grazed in the head, another was hit in the leg and foot and the other was shot in the neck and shoulder, Richard said. None are talking to police, she added.
Richard said officials learned of the shooting when the student grazed in the head made his way back to the school and was pulled inside by an administrator.
Terri Minor said her 17-year-old nephew, Eugene Minor, was shot in the neck. She said he and his two friends who were wounded were trying out for the basketball team.
Police surrounded a home in the Beechview neighborhood and were ordering a possible suspect to come out. Residents were ordered to stay inside with their doors locked.
Witnesses said the shooter or shooters were dressed in black and retreated into woods around the school, Richard said. She could not confirm that the gunman or gunmen emerged from the woods.
WPXI-TV reported that a shotgun may have been used and that police found shell casings in the woods.
About 1,400 students are enrolled at Brashear, the city's largest high school.